4) If you are financing the second, third, fourth etc..properties, aren't the DTI numbers astronomical?

I have a similar setup, a large 4br home with an accessory or mother in law quarters in the back with a private entrance for both.

Do you remove and reset trim (quarter round or shoemold)?

I don't always want to "quit or pay" on the fourth day of the month. 

When you file form 3115 with automatic consent your taxpayer account is credited within 30 days with the adjustment, meaning your next quarterly tax payment(or multiple payments if the adjustment is large enough) will be reduced by the corresponding amount.

Our standard practice is to do them every quarter, but our clients are allowed to have us do them less if they want.

They have such and such time to be out and so fourth.

If you have some $100,000 rental houses that net $100/door per month in cash flow, do you want to give three-fourths of that away in return for the additional liability protection offered by a different LLC for each?

Sometimes calling the 3rd Thursday of the month after 5pm works well as they are often working after hours to prepare for end of the month/quarter reports and their assistant or gate keeper is gone for the evening.  3).  

Also keep in mind, if you are subject to quarterly estimated taxes, you will need to pay your taxes earlier otherwise you will be subject to an estimated tax penalty